Search Publications
Remote Sensing of H from Ulysses and Galileo
McComas, D.; Witte, M.; Pryor, W. +5 more
We model interplanetary H Lyman-α (Lα) observations from Galileo UVS (Ultraviolet Spectrometer) and EUVS (Extreme Ultraviolet Spectrometer) (Hord et al., 1992) and the Ulysses interstellar neutral gas (GAS) instrument (Witte et al., 1992). EUVS measurements near solar maximum (max) in 1990 1992 have a peaked brightness maximum upwind due to a rath…
Discovery of an absorbed cluster of galaxies (XMMU J183225.4-103645) close to the Galactic plane with XMM-Newton
Parmar, A. N.; Lumb, D.; Nevalainen, J. +3 more
During an XMM-Newton observation of the galactic supernova remnant G21.5-09 a bright, previously uncatalogued, source (XMMU J183225.4-103645) was detected 18' from G21.5-09. The European Photon Imaging Camera data inside 1' (180 h50-1 kpc) radius are consistent with a source at a redshift of 0.1242 +/- 0.00030…
Ion Acoustic Waves in the Heliosphere
Lin, Naiguo; Kellogg, P. J.; MacDowall, R. J. +1 more
Observations of ion acoustic waves in the solar wind during the first and second orbit of the Ulysses spacecraft are presented. The observations show variations of the wave activity with the heliolatitude and with the phase of the solar cycle. The interrelationships between the wave intensity and the electron heat flux and the ratio of electron to…
An XMM-Newton view of the serendipitous sources in the PKS0312-770 field
Gondoin, P.; Guainazzi, M.; Lumb, D. H.
We describe an XMM-Newton observation of the PKS0312-770 field, which facilitates the spectral analysis of serendipitous sources previously detected by CHANDRA. The combination of larger effective area and longer exposure duration allows a significant increase in detected photons, and a lower limit in source detection sensitivity. In particular th…
Radial velocities of dwarf spheroidal galaxies in the M 81 group
Burenkov, A. N.; Sharina, M. E.; Karachentsev, I. D.
Long-slit observations of 4 dwarf spheroidal galaxies in the M 81 group are presented. We have obtained the heliocentric velocity of a globular cluster candidate located near the center of DDO 78 to be 55 +/- 10 km s-1 by cross-correlation with template stars. We estimated a heliocentric radial velocity of -116 +/- 21 km s-1 …
A ROSAT medium-sensitivity Galactic plane survey at 180°< l < 280°
Briggs, K. R.; Micela, G.; Favata, F. +3 more
We have performed a moderately deep soft X-ray (0.1-2keV) survey of the Galactic plane using pointed observations with the ROSAT Position Sensitive Proportional Counter (PSPC). The survey is more than an order of magnitude more sensitive than previous X-ray surveys near the Galactic plane. The data consist of nine fields each of ~10ks exposure, po…
An Estimate of Drift Effects in Various Models of the Heliospheric Magnetic Field
Potgieter, M. S.; Burger, R. A.; van Niekerk, Y.
We use a comparison with other models to estimate how significant drifts will be in the Fisk model of the heliospheric magnetic field (HMF). We also show that drifts are still be present in an idealized field model for the period shortly after the solar polarity reversal.
Cosmic Ray Transport in a Heliospheric Magnetic Field with Non-Polar Coronal Holes
Jokipii, J. R.; Kóta, J.
The simple tilted dipole picture of Corotating Interaction Regions which prevailed during the first polar pass of Ulysses no longer applies since the Sun entered a more active phase. Recent observations show that CIRs still persist, though the large polar coronal holes of solar minimum shrink to smaller areas and move to lower latitudes. We presen…
Non-LTE Modeling of Nova Cygni 1992
Baron, E.; Hauschildt, Peter H.; Starrfield, S. +1 more
We present a grid of nova models that have an extremely large number of species treated in non-LTE and apply it to the analysis of an extensive time series of ultraviolet spectroscopic data for Nova Cygni 1992. We use ultraviolet colors to derive the time development of the effective temperature of the expanding atmosphere during the fireball phas…
Formation of Fe X-Fe XIV coronal lines in the accretion shock of T Tauri stars
Lamzin, S. A.; Stempels, H. C.; Piskunov, N. E.
Specific intensities of the strongest Fe x-Fe xiV\ coronal lines were calculated in the framework of our accretion shock model (Lamzin \cite{Lamzin1998}). These lines are formed in a region immediately behind the front of the accretion shock, therefore, the gas velocity in the line formation region is close to 1/4 of the infall velocity. It appear…